Automatic determination of leakage rates in evacuated inoperative vacuum vessels

摘要

A mechanical leakage causes the scriber of a pressure recorder to present a straight-line graph when a logarithmic scale is used and an increase of pressure due to vaporization in the vessel produces a curve. A computer program can be written to distinguish between the two effects and calculate separate leakage and vaporization rates. Equations, which link rates of pressure increase and vessel volumes, are used. Calculations are carried out at regular intervals between 100 and 1000 seconds. Alarm limits for vacuum losses between 1 to 100 mbar are specified.